A nurse takes a swab sample from a resident for COVID-19 test at a testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 25, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Ji Chunpeng)
A nurse (R) helps a doctor take off the protective suit at a COVID-19 testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 25, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Ji Chunpeng)
A doctor talks to a volunteer at a COVID-19 testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 21, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Ji Chunpeng)
A volunteer (2nd L) works as local residents hold umbrellas for him at a stadium in Gulou District of Nanjing, capital of east China's Jiangsu Province, July 25, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Ji Chunpeng)
A staff sprays disinfectant at a COVID-19 testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 24, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Li Bo)
A volunteer rechecks registration information at a COVID-19 testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 24, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Li Bo)
Medical workers take swab samples from residents for COVID-19 test at a testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 24, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Li Bo)
A doctor works at a COVID-19 testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 25, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Ji Chunpeng)
A medical worker takes a swab sample from a child for COVID-19 test at a testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 24, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Li Bo)
A doctor works at a COVID-19 testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 21, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Ji Chunpeng)
Doctors prepares to work at a COVID-19 testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 21, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Ji Chunpeng)
A volunteer (R) helps residents make COVID-19 test reservations at a COVID-19 testing site in Jiangning District of Nanjing, capital of east China's Jiangsu Province, July 24, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Li Bo)
Volunteers wait for citizens to register information at a stadium in Gulou District of Nanjing, capital of east China's Jiangsu Province, July 25, 2021. Nanjing, a mega-city with a population of more than 9.3 million, has launched a second round of all-inclusive nucleic acid testing and urged residents not to leave the city unless necessary. (Xinhua/Ji Chunpeng)
